1. Field of the Invention
The present invention relates generally to a craniocervical orthosis in which an infant's cranium is positioned while the infant is sleeping to prevent and correct cranial deformities. More specifically, the invention relates to a craniocervical orthosis and method for preventing and correcting any non-synostotic deformity of the side and posterior aspects of an infant's head.
2. Background of the Invention
At birth, the six cranial bones comprising an infant's skull are spaced far enough apart to allow the skull to rapidly grow during the first months of the infant's life. This spacing also allows the bones to overlap so the infant's head can pass through the birth canal without compressing, and thereby damaging, the infant's brain. Eventually—some time between three and six years of age—the cranial bones will fuse and remain fused for the rest of the child's life.
During an infant's normal growth, forces within the infant's skull are directed outward and are constant and equally distributed on the inner surface of the growing skull causing the skull to expand. Accordingly, a decrease of the intracranial pressure will cause a reduced head size. Similarly, an increase in intracranial pressure will cause an increased head size.
Fibrous bands of tissue, called cranial sutures, fill the space between the bones and connect the bones of the skull to each other. These cranial sutures are strong and elastic, providing a flexibility to the skull to allow rapid brain growth during the first months of life. Without the sutures, a child would suffer brain damage due to constriction of the brain during the period of normal growth.
During the first few months of an infants' life, however, the infant is most susceptible to the formation of synostotic or non-synostotic deformities in the cranium. Synostotic deformities are a result of craniosynostosis, which is a birth defect of the skull characterized by premature closure of one or more of the cranial sutures. Craniosynostosis can be hereditary or the result of a metabolic disease, and is characterized by an abnormally-shaped skull and potential for abnormal intracranial pressure, mental retardation, seizures, and blindness.
On the other hand, non-synostotic deformities, in which the cranial sutures remain open, are caused by environmental conditions, including premature birth, torticollis (twisting of the neck muscles beyond their normal position), or the preferred sleeping position of the child. In addition, neurological abnormalities, such as paralysis, cerebral palsy, or some sort of developmental delay, may predispose a child to cranial positioning problems. Non-synostotic deformities are also called positional deformities.
Synostotic and non-synostotic deformities manifest themselves in a variety of ways. Plagiocephaly, for example, is a cranial deformity resulting in an asymmetric head shape. Plagiocephaly consists of a focal area of flattening in the anterior or posterior aspect of one side of the head, which also commonly produces additional compensatory deformities in adjacent areas of the skull, skull base, and face, including the orbital (eye) and mandibular (jaw) structures. This deformity most commonly occurs in the posterior aspect of the head (posterior plagiocephaly), resulting in a focal area of flattening on that side and a compensatory prominence, or bulge, on the other side. In addition, the deformity produces anterior displacement of the ear, ear canal, temporomandibular (jaw) joint, forehead and orbital structures on the same side. Cranial deformities may also be classified, inter alia, as brachycephaly (a short, wide head shape), scaphocephaly (a long, narrow head shape), and turricephaly (a pointed head shape).
Non-synostotic posterior plagiocephaly is a very common problem for which parents seek evaluation and recommendations from their family physician or pediatrician. The incidence of this abnormality has increased significantly since publication of recommendations by the American Academy of Pediatrics that neonates (infants) should be put to sleep on their back rather than face down. These recommendations were made to reduce the incidence of Sudden Infant Death Syndrome (SIDS) by eliminating airway and respiratory compromise in the prone (face-down) position, which the Academy considered a possible contributor to the SIDS problem.
Brain growth is responsible for the growth and shaping of the skull, which results from slow, gradual separation of the bones at the cranial sutures. This separation allows for the addition of new bone onto the peripheral edges of the existing bone, producing gradual bone enlargement and reshaping of each bone. As the head enlarges, new bone is added to each bone in an inwardly directed fashion producing an inner surface concave shape to the overall bone. Any force or pressure applied to the exterior surface of the bone will re-direct the growth of bone added to the edges. New bone will be added in a more linear direction, thus reducing the inner surface concavity or producing “flattening” of the bone. Growth of bone does not stop; rather, it is redirected. Therefore, externally applied pressure (e.g., contact with an orthosis) reduces or stops outward growth or migration in that area, and redirects the growth to occur in a direction that is perpendicular to the applied force, which is tangential to the bone surface in that location. Uniform expansion of the remaining bones and sutures, which comprise the cranial vault, is rare. Instead, relative increased growth and expansion of the areas most adjacent to the “flattened” area tends to occur.
Treatment may come in the form of prevention or correction. Regarding prevention, the focus should be to reduce the duration that external pressure is applied to a localized area of the skull. This can be accomplished by moving the same external force to different areas of the skull. This is only achievable by re-positioning the patient's head, which is not possible in a large number of infants (e.g., those having immobility from torticollis). An alternative way to accomplish this is to enlarge the surface area of contact, which reduces the amount of pressure on the specific area, although it still typically results in at least some contact at the area of desired growth. It is also important to restrict the compensatory overgrowth that forms abnormal prominent areas in locations that are perpendicular and adjacent to the area of applied force. This allows for re-direction of growth and expansion in an appropriate normal direction. Devices used for prevention must maintain these properties, but still allow for expected progressive growth.
Prolonged immobility of the head will eventually lead to the development of a positional deformity. The etiology of the immobility may be neurologic/developmental, muscular, skeletal (vertebral) or simply from resting/sleeping preference in the absence of any known cause. Persistent immobility will allow for lateral and posterior deformities to develop.
Despite public knowledge and education regarding the development of these deformities and preventative measures, because infants are usually born with normal head shapes, it appears economically irrational to go through the expense and trouble of obtaining a preventative device if no deformity appears to be present. Development of these deformities is insidious, slowly occurring over weeks and easily overlooked. Frequently, only when the condition is obvious is intervention considered.
Treatment by “repositioning,” also called “mobilization”—that is, the act of another person moving the infant's head from side to side at regular intervals—is ineffective for treating or preventing these deformities due to the inherent problems associated with such a method of treatment. Simply put, it is very difficult to keep the child's head in the same position for extended periods of time, as the natural inclination of the child is to revert to his or her preferred sleeping position. Moreover, because “mobilization” is ideally performed every two to three hours, the infant requires constant attention throughout the night, and it is therefore not a practical treatment option. Similarly, children with torticollis cannot be effectively “mobilized” due to the tendency of the head to rotate as a result of involuntary contraction of the neck muscles. In both of these cases, the resulting position of the head—whether by preference or immobility—is most likely not the desired position for correction of deformities and is, as noted above, the cause of deformity in the first place.
To the extent treatment by repositioning might be effective when the above-referenced parameters are satisfied—i.e., a child who does not tend to revert to a preferred sleeping position and is not immobilized due to torticollis, and who can be mobilized regularly every two to three hours—children treated with prevention in this manner still do not obtain a perfectly normal head shape, because the supporting apparatus remains in contact with the skin and conforms the head to an abnormal shape. As a result, forces still act on already-flattened regions of the cranium and inhibit growth at precisely the area of the cranium where growth should be promoted. Due to this ineffectiveness, a large number of these children require additional treatment from five to ten months of age to correct persistent or progressive deformities.
The most common adjuncts available to assist with repositioning are flat- and wedge-shaped foam pads. For example, U.S. Pat. No. 6,473,923 (filed Nov. 22, 2000) (issued Nov. 5, 2002) discloses a body pillow and head positioner attached to a mat. The device is intended to maintain the infant's supine position—i.e., lying on the back, face upward—while reducing the risk of positional plagiocephaly by causing the head to rotate to the side while maintaining the infant's supine position.
One goal for correction of an existing deformity is to eliminate the external forces acting on the flattened area. As with prevention, improved correction can be achieved by providing external forces acting on the compensatory prominent areas of the skull, thereby reducing growth that occurs in these areas and redirecting growth towards a more normal direction and shape. Allowances for growth are also required for correction, but cannot compromise the mechanical ability of a device to correct the existing deformity.
Corrective treatment most often is by application of a custom-made external orthosis, or helmet. See, e.g., Corrective Infant Helmet, U.S. Pat. No. 6,592,536 (filed Jan. 7, 2000) (issued Jul. 15, 2003); Therapeutic and Protective Infant Helmets, U.S. Pat. No. 4,776,324 (filed Apr. 17, 1998) (issued Oct. 11, 1998). Such devices provide an expanded area over the site of the deformity, thereby allowing for correction of the deformity over a three to six month period of time related to brain and skull growth and subsequent reshaping. This prolonged time of use is necessary because of the reduced rate of brain and skull growth during the six- to twelve-month time frame. Due to a decrease in the rate of brain and skull growth to approximately fifty percent of the rate from birth to six months and increased stiffness of bones and cranial sutures, the recommendation is to wear the helmet continuously for twenty-three hours each day for up to twelve months. But despite extended use of these helmets, deformities rarely return to a normal shape. In addition, many health insurance companies and programs refuse to pay for these devices, leaving a large number of infants with no available treatment because of the relatively high cost of the helmets.
Similar to the preventative approaches discussed supra, another proposed approach to correct existing cranial deformities is to soften the material on which the infant's head rests by using a foam pad or memory foam pillow. This method allows the redistribution of inwardly directed forces, but fails to adequately correct cranial deformities because the softened material conforms to the already-abnormal head shape. Specifically, the material still contacts, and therefore applies forces to, the already flattened areas of the head and reduces forces that should be applied at the abnormal cranial bulges. Preventing cranial deformities with this approach is also ineffective because forces continue to act directly on a focused area of the head rather than the entire cranial vault. Because these pads and pillows are not shaped like a normal infant cranium, but are generally flat, forces acting on the cranium from these devices result in cranial flattening, and therefore an abnormal head shape, because the head conforms to the shape of the material (i.e., flat) at the point of contact.
Still another approach is to suspend the infant's head on a flexible material, which, for example, may be a net with an open weave that keeps the infant's head slightly elevated over the resting surface. See Method and Apparatus to Prevent Positional Plagiocephaly in Infants, U.S. Pat. No. 6,052,849 (filed Mar. 18, 1999) (issued Apr. 25, 2000). Although the use of an elastic stretchable material or netting may be slightly better than regular foam for preventing the development of flattened areas, these devices also do not effectively promote normal shaping due to the continuous application of external forces directed at the posterior aspect of the infant's head. In the case of correction, the flexible material will still conform to the already-abnormal head shape and exert forces on the flattened areas. In the case of prevention, the weight of the cranium on the flexible material will tend to immobilize the cranium, which results in prolonged contact of non-uniform forces around the cranium and, again, is precisely the wrong methodology for maintaining an already normal cranial shape. As with the “softened material” approach previously described, forces acting on a smaller area of the head results in reduced cranial growth and expansion because the head conforms to the shape of the material, thus resulting in an abnormal head shape in which the frontal areas are wider than the posterior aspect of the head because the material is applied only to the posterior aspect of the cranium, with the application of constricting forces.
After ten to twelve months of age, little, if any, correction of a cranial deformity can be accomplished with non-operative treatment because of reduced velocity of brain and skull growth, increased thickness of bone, and reduced flexibility of the cranial sutures. Surgical intervention is typically the only effective treatment for moderate to severe deformities in children over twelve months of age.
Alternative methods for correcting this condition without the use of a helmet do not directly address the cause of the problem, and therefore do not effectively treat the condition. All other products and devices, including foam, elastic (and therefore flexible) material or netting, merely distribute or disperse forces over a focused area of the head Because these products and devices remain in continuous contact with the skin, they conform the cranium to the abnormal shape, including the abnormally flattened areas. Thus, the prior art does not remove or eliminate the external forces at flattened areas of the cranium, but rather maintains an abnormal cranial shape and promotes a static deformity.
Finally, attempts to prevent and correct such deformities with the use of headrests also exist. With the exception of the present invention and U.S. Pat. No. 4,825,487 (issued May 2, 1989) to Eberl (hereinafter “Eberl”), the existing headrests are “low profile” devices, which extend only a maximum of 35 mm anterior of the most posterior position of contact with the infant's skull (about 30% or less of the anterior-posterior distance) and only contact the very or most posterior area of the head. See, e.g., WO 2006/102407 (published Sep. 28, 2006); European Patent No. EP 1 665 958 (filed Aug. 25, 2004); New Zealand Patent No. 510,421 (filed Mar. 8, 2001). However, the low profile (i.e., posterior only) headrests are ineffective based on bio-mechanics of such devices, as lateral support is necessary in order to achieve effective prevention and treatment
These available and proposed low-profile devices provide insufficient support and positioning to overcome the problem of immobility leading to development and progression of positional deformities. These deformities develop despite any differences or modifications in shape, size, or consistency—that is, prevention or any level of correction with low profile devices will require turning of the head, and any prevention or correction achieved would be due to “repositioning” treatment as described supra, thus making the device unnecessary. The treatment provided in this situation is repositioning, not the low profile device. And as noted above, the ability to reposition or turn the head is a luxury and is not possible in a large number of instances. Lateral support, however, allows one to overcome the problem of immobility, which is not achievable with a low-profile device.
While Eberl would not be considered a “low profile device” as discussed supra, it also provides insufficient lateral support. As shown in FIG. 4 and FIG. 5 of Eberl, the sidewalls are outwardly angled from the longitudinal axis of the device, which inherently means Eberl provides no immediately adjacent lateral support when the infant's cranium is rotated in either direction. In this manner, Eberl is effectively the same as the low-profile devices, but with an added disadvantage that the Eberl sidewalls are excessively high such that a very young infant placed on the Eberl invention is susceptible to the development of obstructive amblyopia due to the obstruction of the visual field/pathway. In addition, Eberl is made from soft, conforming material, which, as noted with respect to foam mattresses and pads, conforms to an abnormal head shape.
Currently there is no specific apparatus available to provide effective corrective and preventative treatment for non-synostotic cranial deformities in the age range of birth to five months. To avoid the difficulties and pitfalls associated with currently available devices aimed at treating non-synostotic cranial deformities, the present invention discloses a corrective headrest for use at the very first recognition of development of a deformity. The headrest and method allow effective treatment during the rapid period of brain and skull growth (birth to six months), thereby providing rapid correction of the deformity. Children with predisposing conditions may require prolonged treatment. Early effective treatment is the key to providing complete correction of these deformities.